[clang-tools-extra] 20bce6d - [clang-tidy] Teach `performance-faster-string-find` about `starts_with`, `ends_with`, and `contains` (#182633)

[via cfe-commits]

Author: Victor Chernyakin
Date: 2026-02-21T11:02:41-07:00
New Revision: 20bce6de5e72aa7129869315e3a23972bd897285

URL: https://github.com/llvm/llvm-project/commit/20bce6de5e72aa7129869315e3a23972bd897285
DIFF: https://github.com/llvm/llvm-project/commit/20bce6de5e72aa7129869315e3a23972bd897285.diff

LOG: [clang-tidy] Teach `performance-faster-string-find` about `starts_with`, `ends_with`, and `contains` (#182633)

These aren't "find" functions per se, so they don't totally match the
check name, but the same optimization is applicable to them (for
example, see
https://en.cppreference.com/w/cpp/string/basic_string_view/starts_with.html).
This optimization could be expanded to `operator+=` as well, but that's
a bit more involved, so I'm not doing it in this PR.

Added: 
    

Modified: 
    clang-tools-extra/clang-tidy/performance/FasterStringFindCheck.cpp
    clang-tools-extra/docs/ReleaseNotes.rst
    clang-tools-extra/docs/clang-tidy/checks/performance/faster-string-find.rst
    clang-tools-extra/test/clang-tidy/checkers/performance/faster-string-find.cpp

Removed: 
    


################################################################################
diff  --git a/clang-tools-extra/clang-tidy/performance/FasterStringFindCheck.cpp b/clang-tools-extra/clang-tidy/performance/FasterStringFindCheck.cpp
index 7c90130c826f0..52a4d70e15265 100644
--- a/clang-tools-extra/clang-tidy/performance/FasterStringFindCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/FasterStringFindCheck.cpp
@@ -67,13 +67,14 @@ void FasterStringFindCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
 void FasterStringFindCheck::registerMatchers(MatchFinder *Finder) {
   const auto SingleChar =
       expr(ignoringParenCasts(stringLiteral(hasSize(1)).bind("literal")));
-  const auto StringFindFunctions =
-      hasAnyName("find", "rfind", "find_first_of", "find_first_not_of",
-                 "find_last_of", "find_last_not_of");
+
+  const auto InterestingStringFunction = hasAnyName(
+      "find", "rfind", "find_first_of", "find_first_not_of", "find_last_of",
+      "find_last_not_of", "starts_with", "ends_with", "contains");
 
   Finder->addMatcher(
       cxxMemberCallExpr(
-          callee(functionDecl(StringFindFunctions).bind("func")),
+          callee(functionDecl(InterestingStringFunction).bind("func")),
           anyOf(argumentCountIs(1), argumentCountIs(2)),
           hasArgument(0, SingleChar),
           on(expr(hasType(hasUnqualifiedDesugaredType(recordType(hasDeclaration(
@@ -94,10 +95,7 @@ void FasterStringFindCheck::check(const MatchFinder::MatchResult &Result) {
                                "a single character; consider using the more "
                                "effective overload accepting a character")
       << FindFunc
-      << FixItHint::CreateReplacement(
-             CharSourceRange::getTokenRange(Literal->getBeginLoc(),
-                                            Literal->getEndLoc()),
-             *Replacement);
+      << FixItHint::CreateReplacement(Literal->getSourceRange(), *Replacement);
 }
 
 } // namespace clang::tidy::performance

diff  --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 77be492d4093e..cf8dd0dba9f12 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -230,6 +230,11 @@ Changes in existing checks
 
   - Improved the ignore list to correctly handle ``typedef`` and  ``enum``.
 
+- Improved :doc:`performance-faster-string-find
+  <clang-tidy/checks/performance/faster-string-find>` check to
+  analyze calls to the ``starts_with``, ``ends_with``, and ``contains``
+  string member functions.
+
 - Improved :doc:`performance-inefficient-vector-operation
   <clang-tidy/checks/performance/inefficient-vector-operation>` check by
   correctly handling vector-like classes when ``push_back``/``emplace_back`` are

diff  --git a/clang-tools-extra/docs/clang-tidy/checks/performance/faster-string-find.rst b/clang-tools-extra/docs/clang-tidy/checks/performance/faster-string-find.rst
index 28bd08d8aaa11..a7fb97197460e 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/performance/faster-string-find.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/performance/faster-string-find.rst
@@ -24,6 +24,7 @@ Options
 
    Semicolon-separated list of names of string-like classes. By default only
    ``::std::basic_string`` and ``::std::basic_string_view`` are considered.
-   The check will only consider member functions named ``find``, ``rfind``,
-   ``find_first_of``, ``find_first_not_of``, ``find_last_of``, or
-   ``find_last_not_of`` within these classes.
+   Within these classes, the check will only consider member functions named
+   ``find``, ``rfind``, ``find_first_of``, ``find_first_not_of``,
+   ``find_last_of``, ``find_last_not_of``, ``starts_with``, ``ends_with``, or
+   ``contains``.

diff  --git a/clang-tools-extra/test/clang-tidy/checkers/performance/faster-string-find.cpp b/clang-tools-extra/test/clang-tidy/checkers/performance/faster-string-find.cpp
index e52441035e15f..83824c62494e7 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/performance/faster-string-find.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/performance/faster-string-find.cpp
@@ -14,6 +14,9 @@ struct basic_string {
   int find_first_not_of(const Char *) const;
   int find_last_of(const Char *) const;
   int find_last_not_of(const Char *) const;
+  bool starts_with(const Char *) const;
+  bool ends_with(const Char *) const;
+  bool contains(const Char *) const;
 };
 
 typedef basic_string<char> string;
@@ -28,6 +31,9 @@ struct basic_string_view {
   int find_first_not_of(const Char *) const;
   int find_last_of(const Char *) const;
   int find_last_not_of(const Char *) const;
+  bool starts_with(const Char *) const;
+  bool ends_with(const Char *) const;
+  bool contains(const Char *) const;
 };
 
 typedef basic_string_view<char> string_view;
@@ -87,6 +93,15 @@ void StringFind() {
   Str.find_last_not_of("a");
   // CHECK-MESSAGES: [[@LINE-1]]:24: warning: 'find_last_not_of' called with a
   // CHECK-FIXES: Str.find_last_not_of('a');
+  Str.starts_with("a");
+  // CHECK-MESSAGES: [[@LINE-1]]:19: warning: 'starts_with' called with a
+  // CHECK-FIXES: Str.starts_with('a');
+  Str.ends_with("a");
+  // CHECK-MESSAGES: [[@LINE-1]]:17: warning: 'ends_with' called with a string
+  // CHECK-FIXES: Str.ends_with('a');
+  Str.contains("a");
+  // CHECK-MESSAGES: [[@LINE-1]]:16: warning: 'contains' called with a
+  // CHECK-FIXES: Str.contains('a');
 
   // std::wstring should work.
   std::wstring WStr;